The present invention is directed to an extendible and retractable pole which may be mounted for vertical or horizontal deployment for traffic control, such as controlling the movement of trucks toward and away from a loading dock or controlling the movement of vehicles in other situations.
Many mechanical and electrical devices have been produced over the years in an attempt to increase safety at loading dock areas. All of these devices have had significant problems to the extent that the desired safety factor has not been achieved.
The mechanical devices are generally of the type which provide a physical restraint to prevent the truck from pulling away from a loading dock accidentally or intentionally while a loading or unloading operation is still being performed. Such mechanical devices however have proven to have high maintenance costs and do not work on all types of trucks. Numerous configurations of mechanical devices have been tried and new ICC bar regulations threaten to complicate the design process of such mechanical restraining devices.
The electrical devices utilized in the past include traffic lights, horns and electric wheel chocks. However, all of these have proved to be inadequate in order to achieve the desired safety factor. The principle difficulty with such electrical devices is that if a truck driver is not aware of the device, he can still pull away from or back into a dock without knowing of any danger.
An extensive review of accident reports at loading docks provided by OSHA and surveys with building owners revealed a surprising statistic. In well over 90% of personal injury cases, the cause of the accident was miscommunication. Frequently a driver did not know that someone was working on a dock or had not finished loading a truck. A further review showed that most of the accidents occurred while backing into the loading dock, not pulling out prematurely.
After review of the statistics and surveys, one common denominator began to appear. It became clear that if some kind of signal device could be provided in front of the loading dock and in front of the truck driver, most of the accidents could be avoided. If you can put some type of physical barrier in the path of a driver, he will not run over it. While several types of existing barriers are known, such as railroad crossing gates or barriers which can be pivoted between a horizontal ground level position and a vertical upstanding position, such barriers generally are unacceptable since the barrier would interfere with truck positioning as well as snow removal on the dock pad. Furthermore, if such rigid devices were accidentally hit by the truck, the barrier would be destroyed.
Examples of such barriers are found in the U.S. patents to Quante (U.S. Pat. No. 4,713,910), Fletcher (U.S. Pat. No. 4,901,071) and Caldwell (U.S. Pat. No. 5,146,710). The device in each of these patents is comprised of a pole which can be pivoted from a horizontal ground level position to a vertical position to provide a barrier post for parking lots and passageways. The patent to Quante also discloses an embodiment wherein the pole can be vertically retracted into a hole in the ground. Each of the barrier posts disclosed in these patents would be severely damaged, generally beyond repair, if struck by a vehicle.
Traffic barriers used in conjunction with a toll facility or a parking facility are usually comprised of a pivoted gate or arm mounted for pivotal movement about a horizontal axis on a support post or column. Such gates or arms are usually made of wood or rigid plastic material which will break off upon accidental impact by a vehicle to prevent damage to the pivot mechanism. Even so, the replacement of a broken gate is expensive and time consuming. Such pivoted gates are sometimes accidentally lowered onto a vehicle causing dents or scratches in the vehicle body.